Resistance and Resistor

In Wikipedia, resistance is a measure of the degree to which an object opposes an electric current through it. The SI unit of electrical resistance is the ohm. Its reciprocal quantity is electrical conductance measured in siemens. Electrical resistance shares some conceptual parallels with the mechanical notion of friction.

The resistance of an object determines the amount of current through the object for a given voltage across the object.

where

R is the resistance of the object, usually measured in ohms, equivalent to J·s/C²

V is the voltage across the object, usually measured in volts

I is the current through the object, usually measured in amperes

For a wide variety of materials and conditions, the electrical resistance does not depend on the amount of current through or the amount of voltage across the object, meaning that the resistance R is constant.

In electronic, a object which gave resistance is call resistor. Resistor had 2 terminal and color code at their body. Color at the resistor's body (look picture above) had value. The value mean amount of resistance at resistor.